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WIDAR is running

Ken Tapping, December 5, 2012

In the sky this week…

Jupiter rises around 4 pm.

Saturn and Venus lie close together and rise around 5 am.

The Moon will reach Last Quarter on the 6th.

A few days ago we had a presentation at our observatory of the first observations resulting from an important US-Canadian partnership. The objective of this collaboration was to upgrade the Very Large Array (VLA), a radio telescope comprising 27 25-metre diameter dish antennas, scattered over the desert near Socorro, New Mexico. This new instrument brings our radio astronomy capabilities in line with those of the new optical telescopes. Among other things this will make it easier to combine the radio and optical data to better understand what is going on out there.

Most objects in the universe produce no light and are not lit up by any nearby stars. However they give off radio waves, which we can observe with radio telescopes. We can then take the data and make images, showing what we would see if our eyes could detect radio waves, or we can present the information in many other ways.

The VLA was a cutting-edge instrument for decades. However, eventually we arrived at a point where the problems to be addressed needed something more powerful. So it was decided to upgrade it. The antennas and radio receivers were redesigned, so that they could collect more useful information, more quickly. This would result in the flood of data from the instrument becoming a tsunami. Something new would be needed to handle this unprecedented flow of data.

That's when engineers at our observatory came up with an idea for a completely new number cruncher, which would be able to deal with the data from the upgraded VLA. It was called WIDAR, which stands for "Wideband Interferometric Digital ARchitecture". Canada proposed providing this number cruncher to the US for use on the upgraded VLA, as a part of a Canadian partnership in this and other instruments. This would give Canadian astronomers guaranteed access to more front-line research tools. The offer was accepted; WIDAR was built and shipped to the US, and it is now in action. The resulting combination of US and Canadian technical innovation promises to do for radio astronomy what the Hubble Space Telescope has done for visible light astronomy.

One of the images obtained with the upgraded instrument showed a distant galaxy with two huge jets of material flowing out. The image was so detailed we could see that the material in one of the jets had been emitted in a series of supersonic burps, each with its own shock wave. There was a radio image of the planet Neptune, looking right through the atmosphere at what was underneath. It looked like higher ground around the equator and near the poles, and flatter terrain around the mid-latitudes. Of course that terrain need not be rock. In the frigid outer reaches of the Solar System, it could be ice or frozen hydrocarbons.

Things we can do with what is now named the Jansky VLA, after a pioneer radio astronomer, include looking closely at the birth of new stars and planets, studying the structure of galaxies and other objects back in the early history of the universe, and searching for intelligent alien life.

Ken Tapping is an astronomer with the National Research Council's Dominion Radio Astrophysical Observatory, Penticton, BC, V2A 6J9.